Way earlier than those ads Drew.

The July 1931, Winchester catalog shows their LEADER, REPEATER, Speed Loads & RANGER shotgun shells with their new STAYNLESS primers.

This 1931 Western Cartridge Co. Super-X ad states "All Western shells now have Non-Corrosive primers."

[Linked Image from i.imgur.com]

I don't have anything Remington dated 1931, but this June 21, 1932, price list is all over KLEANBORE priming --

[Linked Image from i.imgur.com]